Move ebpf to its own directory

Unlike the other images in `base` this needs parts from the
Moby build so move it for now.

Signed-off-by: Justin Cormack <justin.cormack@docker.com>

alpine/base/ebpf/Dockerfile

@@ -1,17 +0,0 @@
-# Tag: cc5bf4d39442741eaeffad79bbd9ae049a9253fa
-FROM mobylinux/alpine-build-ebpf@sha256:da37d99a8baad18e68c44d3807c86977767ed90ce03133b508842eea3b786d3a
-
-ADD kernel-headers.tar /
-ADD kernel-dev.tar /
-ADD kernel-modules.tar /
-RUN cd elfutils-$ELFUTILS_VERSION && \
-  automake && \
-  ./configure --prefix=/usr CFLAGS=-Wno-strict-aliasing && \
-  make -C libelf && make -C libelf install
-RUN mkdir -p bcc/build && cd bcc/build && \
-  cmake .. -DCMAKE_INSTALL_PREFIX=/usr -DLUAJIT_INCLUDE_DIR=/usr/include/luajit-2.1 && \
-  make && \
-  make install
-RUN mkdir -p /usr/local/share/lua/5.1/ && cd ljsyscall && cp -a *.lua syscall /usr/local/share/lua/5.1/
-
-ENV LD_LIBRARY_PATH=${LD_LIBRARY_PATH}:/usr/lib64

alpine/base/ebpf/Makefile

@@ -1,12 +0,0 @@
-KERNEL_FILES=-C ../../kernel/x86_64 kernel-headers.tar kernel-dev.tar kernel-modules.tar
-
-default: ebpf.tag
-
-ebpf.tag: Dockerfile
-	BUILD=$$( tar cf - $^ $(KERNEL_FILES) | docker build -q - ) && [ -n "$$BUILD" ] && echo "Built $$BUILD" && \
-	echo $$BUILD > $@
-
-clean:
-	rm -f ebpf.tag
-
-.DELETE_ON_ERROR: